Electronic devices may be used in railway networks to optimize the control of various parameters associated with railway traffic to raise safety and efficiency standards. One example of electronic devices that are used in railway networks comprises electronic signaling devices, such as semaphores and audiovisual devices, that may be positioned near various electronic control and tracking systems that may part of a railway network, such as wayside equipment.
These systems may exchange data and information with the railway cars in transit —assisting the locomotive operator in carrying out the driving and control operations of the railway cars—and may be able to identify and correct human errors and thus improve the safety level.
The foregoing electronic devices, regardless of functionality and structure, have in common the need to be electrically powered. For example, such devices need to be connected to a voltage source able to supply the appropriate level of current to assure that the appropriate electrical power reaches a given device.
Since these electronic devices are often installed for convenience at the same location or near the signaling equipment, the need to cost-effectively provide the appropriate power level to any such equipment in an integrated fashion is clear. It is known that signaling equipment positioned along the railway line can be relatively far apart from the nearest station (e.g., distances ranging approximately up to a 2200 meters), which raises the issue of providing the appropriate power level to the electronic devices installed along the railway line.
In many installations there are no spare cables available and it becomes problematic to provide additional power lines for new electronic devices. Generally, the power supply circuit from the semaphore signal lamps, near which the electronic devices may be installed, cannot be used. These lamps typically undergo strict inspections to check their efficiency and verify that the necessary current levels are supplied within set intervals. For example, current that may be diverted from the lamps' power supply circuit to supply circuitry apart from the lamps, could conflict with present safety systems by causing conditions, which could be incorrectly declared as alarms, or conversely missing conditions that should result in alarms.
Accordingly, to electrically power such additional electronic devices, it is generally necessary to have a separate power supply line from the one used by the signaling equipment, e.g., a line that drives a semaphore lamp. This commonly requires installing, for each electronic device, a respective set of power cables spanning distances between adjacent stations. This power cabling requirement may be quite costly and time consuming. For example, such installation would require digging along the railway to accommodate these power cables whose combined length could reach up to hundreds of kilometers.
In view of the foregoing, it is desirable to provide a power supply system for the electronic circuitry located along the railway network that doesn't require new cables dedicated to that use, but rather uses existing signaling cables. It is further desirable that such a power supply system be compatible with the already deployed equipment on the railway network and especially with the safety devices and the procedures pertaining to them.